1. Field of the Invention
The present invention relates to projection devices such as liquid crystal projectors, projection image display devices and optical engines such as reflective image display projectors and beam type rear projection television for projecting images on a screen using light pipe devices such as liquid crystal panels or image display elements, and relates in particular to technology for beaming a plurality of light colors onto different light pipe element locations using a rotating multisurface element, and changing the beaming locations in sequence.
2. Description of the Related Art
An optical unit is known in the related art for passing light from a light source through a first and a second array lens, a polarized beam splitter (PBS) and a collimator lens, and then separating the light into red light, blue light and green light by using a plurality of dichroic mirrors, and then changing the optical paths of each separated (colored) light by means of respective rotating prisms and beaming each light onto respectively different locations on a light pipe element (hereafter simply referred to as a display element or image display element) and also scroll each light beam in sequence in a fixed direction on the display element locations.
The above described optical unit of the related art possessed the advantage that assembly of the single plate utilized by the display element was simple. However the optical unit had to be made large in size since a plurality of prisms were required. Further, besides having a high price due to use of a plurality of rotating prisms, a large number of lenses and many dichroic mirrors, the light utilization efficiency was poor because of the many lenses that were used. Also, the rotation phase of a plurality of rotating prisms had to be aligned in order to adjust the display element positions upon which the red, green and blue light were beamed and this alignment was difficult. Furthermore, noise prevention methods were needed due to the plurality of motors being used.
The present invention therefore has the object of providing a compact and low-priced optical unit.
Another object of the present invention is to provide novel and effective image display technology, allow simple position alignment for a plurality of light beamed onto a display element, and provide good light utilization efficiency.
To achieve the above objects of the invention, the optical unit is comprised of a light source, a display element to form an optical image according to an image signal from the light emitted from the light source, a light color separator means for separating the light emitted from the light source into a plurality of light colors, a rotating multisurface element input with a plurality of light colors emitted by the light color separator means for changing the optical path and beaming the plurality of light colors onto different locations on the display element while scrolling the light beam in one direction, and a projection device to light emitted from the display element as a color image.